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Warmer Great Lakes: Nice for a dip, but worrisome

Don Kermeen grew up along the shores of Lake
Superior, and early on he learned a lesson about the mighty lake:
"For most of the year, you don't swim in it unless you're in a
wetsuit."

Not this summer. Superior and the four other Great Lakes have
been at or near record high temperatures for the 30 years such
measurements have been taken - and there's still a month left
before the lakes typically hit their warmest levels of the year.

"It's been awesome," Kermeen, the co-owner of Superior Shores
Resort in Ontonagon, Mich., along Superior's southern shore, said
this week. "I think every single guest I had yesterday was out
swimming. I don't care if they were a kid or in their 60s, they
were out in that water."

A more swimmable Lake Superior may be good for tourism, but the
effect on everything from fishing to wildlife habitat to water
level may be bad. And, while scientists understand why the lakes
are warmer this summer, they don't know if it's a blip or the new
normal.

"I think in general, we don't like to see it, because we're not
sure if it's a good thing for the lakes," said Tom Gorenflo,
tribal fisheries manager for the Chippewa-Ottawa Resource Authority
in Sault St. Marie, Mich. "Everybody is worried about it, and
wondering if it does a fit a larger pattern of global warming,
glaciers melting in Alaska and the like."

Jay Austin, a physics professor at the Large Lakes Observatory
in Duluth, Minn., said there's a simple reason for the warmer
waters: There was little to no ice cover on the Great Lakes last
winter. Open water absorbs sunlight more effectively than
reflective ice and snow.

A buoy in western Lake Superior this week recorded 71 degrees -
1 degree off the record. Lake Superior's normal temperature this
time of year is about 60 degrees.

Two buoys in Lake Michigan were 5 to 6 degrees above normal,
with similar levels in Huron and Erie. Ontario hit about 70 degrees
earlier in July but has since cooled some - an example of the
volatility of lake temperatures, Austin said.

The warmer water could drive down ice levels next winter, Austin
said. But an unusually cold winter could mean more normal water
temperatures next summer.

"There's a ton of variability from year to year in these types
of system," Austin said, but he was quick to add that this year is
"tremendously anomalous." In addition, he said scientists have
monitored a long-term trend toward less ice on Lake Superior over
the last three decades.

Water levels on all five Great Lakes trended downward in the
last decade to near-record lows before rebounding some in recent
years. That has been attributed to warming trends, and warmer lakes
could worsen that problem through greater evaporation.

A big question is what warmer lakes could mean to fish
populations and commercial and sport fishing. Scientists and
fisheries managers are concerned.

Nancy Schuldt, the water quality coordinator of the Fond du Lac
Band of Chippewa Indians in Cloquet, Minn., said area rivers and
wetlands would suffer greatly without a healthy water flow from
Lake Superior - in everything from habitats they rely on for
fishing, to ill effects in growing conditions for the culturally
important wild rice the band harvests every year.

"Even slight warming in our waters and wetlands and we could
see some major upheavals," Schuldt said.

Gorenflo, the tribal fisheries expert in Sault Ste. Marie, said
warmer lake water might heighten the impact of invasive species by
promoting their growth.

Invasive species like zebra mussels have found their way into
the Great Lakes, but so far haven't thrived the way they have in
smaller, warmer lakes, Gorenflo said.

But at least for this year, some fishermen are welcoming the
warmer water. John Steiben, owner of Duluth's Lake Superior
Fishing, a charter fishing business, it's been a great summer for
salmon and lake trout.

"Warmer water seems like it's meant more fish around," Steiben
said. "Whatever is going on, it's been good for us."